Arrangement in emitting electrodes



July 27, 1954 SQHLMAN 2,684,730

ARRANGEMENT IN EMITTI NG ELECTRODES Filed May 27, 1952 IN VEN TOR.

fil 651)? jkhw BY W W Patented July 27, 1954 UNITED STATES ?ATENT OFFICE ARRANGEMENT IN EMITTING ELECTRODES Nils Fredrik Sohlman, Kearny, N. J., assignor to A B Svenska Flaktfabriken, Stockholm, Sweden, a corporation of Sweden 3 Claims.

The present invention relates to an arrangement in emitting electrodes for electro-filters having a plurality of wires suspended between horizontal frames in a framework. In electrofilters of this kind great difficulties are encountered in holding the emitting electrodes stiff enough as the electrodes usually have a length of 3 metres or more. It has therefore heretofore been proposed to arrange springs between the electrodes and to have fastening hooks for the springs in the upper and lower horizontal beams of the framework. The emitting electrodes are, however, put in undamped vibrations by these springs when cleaning the electrodes now and then. Such cleaning is performed by means of separate hammering members, for instance ones of a magnetic type. It has also been proved that the holes for the spring hooks in the two frame beams will result in a weak mechanical strength of the framework. The beams will therefore not maintain their straight form but assume a slight curved one. In addition to the mechanical stress there will also be chemical corrosion by the raw gas at the mounting points of the hooks and at the holes for the hooks through the frame beams. Especially considerable corrosion will occur in the centre of the electrode system, where the mechanical stress is greatest. The object of this invention is to eliminate these disadvantages in electro--filters and to provide a steadier system of emitting electrodes havin easily changeable parts.

The invention is substantially characterized by a plurality of tube pieces fixed at the sides of the frames facing each other and disposed in the longitudinal direction of the frames. The ends of the electrode wires are inserted and bent in these tube pieces. Each electrode is provided with one or more coils at least at its one end adjacent to the framework and its tube piece, said coils extending in the plane of the framework in order to provide a resilient tension of the electrode wires.

According to a convenient embodiment of the invention the electrode wires have the form of a common square wire or a square wire having slightly concave sides in order to facilitate the discharge of the electrode.

The invention will now be more fully described in connection with the accompanying drawing, in which:

Fig. 1 is a view in elevation of an electrode wire and a partial vertical section of the framework of an arrangement of emitting electrodes according to my invention;

Fig. 2 is a vertical section of the electrode wire and framework on the line II-II of Fig. 1, taken at right angles to the plane of Fig. 1.

In the drawing, 1 and I8 are the upper and lower members of the framework. The tube pieces 3 and l 3 are fixed to these frame members, for instance by welding. In the framework the emitting electrodes ll, l2 are suspended having one or more reverse loops 8, [0 at least adjacent to the supporting points 4, I6 of the tube pieces, which latter in turn are fixed to the framework. The ends 6, M of the electrode are inserted in said tube pieces and bent at T and IS. The invention will make it possible for the electrode wires to be held stretched the proper amount. Any vibrations having a great amplitude will be prevented.

The above arrangement has the advantage that a good contact always is obtained between the electrodes and the frame. Contact resistance will thus be eliminated which will otherwise occur in the contact surfaces when using separate spring elements. With respect to the emitting action it is necessary not to exceed a certain diameter of the wire as the amplitude of the discharging corona current otherwise will be reduced under the optimal value. For this purpose square Wires are preferably used when coarse wires are desired owing to mechanical reasons and chemical corrosion. Said square wire has a greater mechanical strength than a wire having a diameter corresponding to that of the inscribed circle and the four side edges of the wire will facilitate the emission from the electrode.

The above-mentioned arrangement will also reduce the bending inward of the framework in such manner that the construction of the fixing points involves elimination of the weakening of the framework, which weakening occurs in the prior construction having holes through the horizontal frames. No chemical corrosion will occur on the plain surface of the framework owing to the elimination of the holes. Any possible corrosion will at most make it necessary to change some tube pieces after a long time of working in corroding gases. Said replacement Will now be more economic and practical by using said fastening method, i. e., welding, than rejecting the whole framework, which usually has been the case.

What I claim is:

1. An electrode structure comprising a pair of eiongated frame members disposed in spaced parallel relation to each other, an elongated tubular element secured to the inner exterior surface of each frame member with the bore of said tubular members extending longitudinally of and parallel to the frame members, and an electrode wire spanning the space between said frame memberssubstantially in the plane thereof and having its opposite end portions disposed in the bores of said tubular members, said electrode wire having therein adjacent at least one of said tubular elements a reverse loop portion extending parallel to said tubular element and. disposed in the plane of the electrode wire.

2. An electrode structure as claimed in claim 1 wherein the electrode wire is of substantially square cross-sectional shape having slightly concave side surfaces to facilitate discharge of the electrode.

4 3. An electrode structure as claimed in claim 1 wherein the end portions of the electrode wire extend entirely through the bores of the tubular members and have their terminal portions projected beyond said tubular members and bent at an acute angle to the aXisof the bores.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,558,007 Smith June 26, 1951 FOREIGN PATENTS Number Country Date 299,476 Germany July 17, 1917 865,813 France June 5, 1941 

